This project will investigate the role of prostaglandins (PGS) in rheumatic diseases and the mechanisms of action of anti-inflammatory drugs. Rheumatoid synovial explants in culture and isolated cells from this tissue will be investigated. We will study the release of PGE2 and examine rheumatoid synovial organ and cell culture media for bone resorption stimulating activity by PGE2 and other labile and stable factors, as well as the inhibition of bone resorbing activity by anti-inflammatory drugs. The concentrations of PGE2 and 6-keto-PGF1-alpha will be measured in synovial fluids from patients with rheumatic diseases, using gas chromatography-mass spectroscopy. The mechanisms of the regulation of PG biosynthesis will be examined utilizing the incorporation of 1-(14C)arachidonic acid precursor into rheumatoid synovial tissue and cells in culture. With this system, we will investigate the mechanism of PG synthesis inhibition by glucocorticoids, and the mechanism of stimulation of PG synthesis by a lymphokine-like factor, produced by human mononuclear cells. The uptake of 1-(14C)arachidonic acid into synovial tissue and measurements of its rate of release may clarify the regulation of PG synthesis and sites of activation and inhibition by various drugs. Immunofluorescent localization of both PGE2 and cyclooxygenase in synovial tissue and cells is planned. The release of activated oxygen species (superoxide anion, singlet oxygen, and hydroxyl radical) from rheumatoid synovial tissue preparations and the effects by anti-inflammatory and other drugs on these species will be investigated.